Download Exterior Angles

Angles in a polygon
• Polygon: A closed plane figure with 3 or more sides
• Regular Polygon: A polygon with all congruent sides
and angles.
• Interior Angles: The angles at each vertex inside a
polygon
Exterior Angles: Angles formed between any side of a shape and a line
extended from the next side.
Supplementary: Angles that add up to 180° . ( an interior angle and its
adjacent exterior angle is supplementary)
Complementary: Angles that add up to 90°.
Sum of the measures of the interior angles of a convex polygon:180° ( n-2)
Example: Find the sum of the angles in a regular pentagon
Angles in a triangle
• Sum of angles in a triangle: Adding all the angles in
a triangle gives 180°.
• Remote Interior angles of a triangle: The two non
adjacent angles to the exterior angle.
• Exterior angle inequality: An exterior angle of a
triangle is greater than either of the remote interior
angles.
Examples
1. Four exterior angles of a pentagon measure 20°,
81°, 33°, and 152°. What is the measure of the of
the fifth exterior angle?
2. Find the sum of the measures of the interior angles
of a convex 22-gon.
3.
What is m∠BCD?